Re: Creating an empty file with Ada.Text_IO

[Maciej Sobczak <see.my.homepage@gmail.com>]

> > What are the recommended ways of:
> > a) creating empty files
> > b) writing a non-terminated line to (or generally at the end of) the file
> 
> Stream I/O.

Right. For those who might be looking for the same in the future:


with Ada.Characters.Latin_1;
with Ada.Streams.Stream_IO;

procedure Test is

   procedure Write_String_To_File (File_Name : in String; S : in String) is
      A : Ada.Streams.Stream_Element_Array (1 .. S'Length);
      F : Ada.Streams.Stream_IO.File_Type;
   begin
      -- convert S to stream elements
      for I in S'Range loop
         A (Ada.Streams.Stream_Element_Offset (I)) :=
            Ada.Streams.Stream_Element (Character'Pos (S (I)));
      end loop;
      
      -- create a stream file and write the content (which might be empty)
      Ada.Streams.Stream_IO.Create (F, Ada.Streams.Stream_IO.Out_File, File_Name);
      Ada.Streams.Stream_IO.Write (F, A);
      Ada.Streams.Stream_IO.Close (F);
   end Write_String_To_File;

begin
   -- empty file:
   Write_String_To_File ("file1.txt", "");
   
   -- file with one, non-terminated line:
   Write_String_To_File ("file2.txt", "abc");
   
   -- file with "one line and a half":
   Write_String_To_File ("file3.txt",
      "abc" & Ada.Characters.Latin_1.LF & "xyz");
end Test;


The above is, of course, platform-specific in the sense that some compatibility between characters and stream elements is assumed. This works everywhere.

Having fun with platform-specific newline variants is left as an exercise to the reader. ;-)

-- 
Maciej Sobczak * http://www.inspirel.com